Resin composition and lid material

Abstract

To provide a resin composition which is excellent in adhesion to a plastic container, especially, a container using polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride and a polylactic acid as materials, and is suitably usable as a sealant layer of a lid material of the container, and a lid material.SOLUTION: A resin composition contains 50 to 94.5 pts.wt. of an ethylene-vinyl acetate copolymer (A), 5 to 30 pts.wt. of a tackifier resin (B), and 0.5 to 25 pts.wt. of fine particles (C) having a primary particle average diameter of 0.001 to 1 μm (here, the total of (A), (B) and (C) is 100 pts.wt.).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition used for a lid material of a container and a lid material having the same as a sealant layer. [Background technology]

[0002] Conventionally, plastic containers made of materials such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, and polylactic acid (PLA), as well as paper-based containers, have been used to package foods, beverages, pharmaceuticals, industrial parts, and other items. The lids used for these containers are made of films that have stable adhesive properties to protect the contents and are easy to peel, allowing them to be opened with appropriate strength when peeled off.

[0003] While many easily peelable films are already known for use with polypropylene and polystyrene containers, no practically effective peelable films have been found for amorphous polyethylene terephthalate (A-PET), crystalline polyethylene terephthalate (C-PET), or PLA containers, the demand for which has been increasing in recent years due to growing environmental awareness. Conventional peelable films have weak adhesive strength, leading to problems with the lids opening due to vibration or dropping during transportation or storage. Furthermore, some A-PET containers are coated with silicone during the production process, further reducing adhesive strength and making these containers unsuitable for practical use.

[0004] Generally, known adhesives for lid sealants include mixtures of polyethylene, ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer, etc., and a tackifier. However, these materials do not provide sufficient adhesive strength. Furthermore, resin compositions comprising an ethylene-α-olefin copolymer, an olefin-based elastomer and / or a styrene-based elastomer, and a tackifier (see, for example, Patent Document 1), and sealing materials comprising an ethylene-α-olefin copolymer, an ethylene-polar monomer copolymer, an ABA block copolymer, and a tackifier (see, for example, Patent Document 2) have also been used, but these do not fully satisfy the adhesive strength required for practical use. Therefore, there is a need for lid materials that can be used effectively in these applications. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 1999-269319 [Patent Document 2] Patent No. 4438108 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a resin composition and a lid material that have excellent adhesion to plastic containers, particularly containers made from polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, and polylactic acid, and that can be suitably used as a sealant layer for the lid material of the container. [Means for solving the problem]

[0007] As a result of intensive research to solve the above problems, the inventors discovered that a resin composition containing an ethylene-vinyl acetate copolymer, a tackifier, and microparticles has excellent adhesion to various plastic containers, and thus completed the present invention.

[0008] That is, the respective aspects of the present invention are the following [1] to

[10] . [1] A resin composition comprising 50 to 94.5 parts by weight of an ethylene-vinyl acetate copolymer (A), 5 to 30 parts by weight of a tackifier resin (B), and 0.5 to 25 parts by weight of fine particles (C) having an average primary particle diameter in the range of 0.001 to 1 μm (wherein the total of (A), (B), and (C) is 100 parts by weight). [2] The resin composition according to the above [1], further comprising 0.5 to 20 parts by weight of a compatibilizer (D) based on 100 parts by weight of the resin composition. [3] The resin composition according to the above [2], wherein the compatibilizer (D) is a hydrogenated product of a polystyrene-polybutadiene-polystyrene block copolymer and has a styrene content of 5 to 20% by weight. [4] For 100 parts by weight of the resin composition, a density measured according to JIS K6922-1 is 860 to 910 kg / m 3 The resin composition according to any one of the above [1] to [3], which contains 5 to 100 parts by weight of an ethylene-α-olefin copolymer (E) in the range of: [5] For 100 parts by weight of the resin composition, a density measured according to JIS K6922-1 is 910 to 940 kg / m 3 and 5 to 100 parts by weight of a low-density polyethylene (F) having a melting point in the range of 98 to 120°C as measured in accordance with JIS K6924-2. [6] The resin composition according to any one of the above [1] to [5], wherein the tackifier resin (B) is at least one selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymer petroleum resins. [7] The resin composition according to any one of the above [1] to [6], wherein the fine particles (C) are calcium carbonate. [8] An adhesive for sealants, comprising the resin composition according to any one of [1] to [7] above. [9] The sealant adhesive according to [8] above, which is for use in containers made of at least one resin selected from the group consisting of polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, and polylactic acid.

[10] A lid material having a configuration including at least two layers: a layer containing the resin composition according to any one of the above [1] to [7], and a supporting substrate layer. [Effects of the Invention]

[0009] According to the present invention, a resin composition can be provided that has excellent adhesion to various types of plastic containers, particularly containers made from polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, and polylactic acid, and is useful for producing a sealant layer for the lid material of the container. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below.

[0011] The resin composition according to one embodiment of the present invention comprises 50 to 94.5 parts by weight of an ethylene-vinyl acetate copolymer (A), 5 to 30 parts by weight of a tackifier resin (B), and 0.5 to 25 parts by weight of fine particles (C) having an average primary particle diameter in the range of 0.001 to 1 μm.

[0012] The ethylene-vinyl acetate copolymer (A) preferably has a vinyl acetate content of 3 to 28% by weight, more preferably 3 to 20% by weight, and even more preferably 3 to 15% by weight. A vinyl acetate content of 3% by weight or more is preferred because the resulting composition has excellent low-temperature heat-sealing properties, while a vinyl acetate content of 28% by weight or less is preferred because the resulting composition has excellent blocking resistance and adhesive strength. The vinyl acetate content in the ethylene-vinyl acetate copolymer can be measured by a method in accordance with JIS K 6924-1.

[0013] The ethylene-vinyl acetate copolymer (A) preferably has a melt flow rate in the range of 0.5 to 30 g / 10 min, particularly 1.0 to 15 g / 10 min, measured in accordance with JIS K 6924-1 at a temperature of 190°C and a load of 21.18 N. A melt flow rate of 0.5 g / 10 min or more is preferred because the resulting sealant adhesive has excellent adhesive strength and high-speed moldability, while a melt flow rate of 30 g / 10 min or less is preferred because the resulting resin composition has excellent stability during molding.

[0014] The ethylene-vinyl acetate copolymer (A) can be obtained by a known production method, and the production method is not particularly limited, but examples thereof include a method of radical polymerization under high pressure using a tubular reactor or a vessel reactor.

[0015] Furthermore, the ethylene-vinyl acetate copolymer (A) may be either a single component or a composition containing two or more types of ethylene-vinyl acetate copolymers.

[0016] The ethylene-vinyl acetate copolymer (A) may be a commercially available product, such as Ultrathene (registered trademark) 537 (trade name, manufactured by Tosoh Corporation).

[0017] The tackifier resin (B) can be any resin that falls within the category of tackifier resins, including synthetic petroleum resin-based tackifiers such as petroleum resins, coumarone resins, and styrene-based tackifiers, and natural resin-based tackifiers such as rosin-based resins, methyl ester-based resins, glycerin ester-based resins, pentaerythritol ester-based resins, terpene-based resins, and modified versions thereof. Among these tackifier resins, synthetic petroleum resin-based tackifiers include aliphatic petroleum resins, aliphatic hydrogenated petroleum resins, aromatic petroleum resins, aromatic hydrogenated petroleum resins, alicyclic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymerized hydrogenated petroleum resins. Tackifier resins selected from at least one selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymerized petroleum resins are particularly preferred due to their excellent adhesion and hygiene, such as reduced odor and coloration.

[0018] The tackifier resin (B) preferably has a softening temperature measured by the ring and ball method in the range of 90 to 150° C., more preferably in the range of 100 to 145° C., and even more preferably in the range of 110 to 140° C. If the softening temperature is 90° C. or higher, the resulting resin composition will have excellent adhesive properties, and if the softening temperature is 150° C. or lower, the tackifier resin will be excellent in terms of production stability.

[0019] Commercially available tackifier resins can be used as the tackifier resin (B). Specific examples of synthetic petroleum resins include (trade names) Arcon (registered trademark) P100, Arcon (registered trademark) P125, Arcon (registered trademark) P140, Arcon (registered trademark) M90, Arcon (registered trademark) M115, and Arcon (registered trademark) M135 (all manufactured by Arakawa Chemical Industries, Ltd.), Imave (registered trademark) S110, Imave (registered trademark) P125 (all manufactured by Idemitsu Kosan Co., Ltd.), and T-REZ (registered trademark) RC115 and T-REZ HA125 (all manufactured by JXTG Nippon Oil & Energy Corporation). Examples of rosin-based (registered trademark) resins include Pine Crystal (registered trademark) KE-311 (manufactured by Arakawa Chemical Industries, Ltd.). Examples of terpene-based resins include YS Resin PX1150 and YS Resin PX1150N (both manufactured by Yasuhara Chemical Co., Ltd.).

[0020] As the fine particles (C), any particles can be used as long as they fall into the category of fine particles, and inorganic fine particles, organic fine particles, etc. can be used. Examples of inorganic fine particles include metal atoms from Groups 1 to 13 of the periodic table (e.g., Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, and Zr) or silicon simple substances, oxides, hydroxides, carbonates, sulfates, silicates, sulfites, and titanates; various clay minerals in which some of these compounds exist; and others, such as iron oxide, zinc oxide, titanium oxide, zirconium oxide, alumina, silica, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, magnesium carbonate, calcium carbonate, barium sulfate, calcium sulfate, sodium sulfate, calcium sulfite, barium titanate, calcium silicate, calcium aluminum silicate, calcium aluminum silicate sodium, clay, wollastonite, glass beads, glass powder, silica sand, silica stone, quartz powder, shirasu, diatomaceous earth, white carbon, iron powder, aluminum powder, kaolin, talc, carbon fiber, carbon nanotubes, mica, and wollastonite. These inorganic fine particles may be used without treatment, or may be surface-treated with a surface treatment agent as needed. In particular, when the particle diameter of the inorganic fine particles is small, it is preferable to perform a surface treatment in order to prevent aggregation of the inorganic fine particles and to disperse them uniformly in the thermoplastic resin. Examples of surface treatment agents include higher fatty acids or derivatives thereof such as esters and salts (e.g., stearic acid, oleic acid, palmitic acid, calcium stearate, magnesium stearate, aluminum stearate, stearic acid amide, stearic acid ethyl ester, stearic acid methyl ester, calcium oleate, oleic acid amide, oleic acid ethyl ester, calcium palmitate, palmitic acid amide, palmitic acid ethyl ester, etc.); silane coupling agents (e.g., vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc.); titanium coupling agents (e.g., isopropyl triisostiaroyl titanate, isopropyl trilauryl myristyl titanate, isopropyl isostearoyl dimethacrylic titanate, isopropyl tridiisooctyl phosphate titanate, etc.).

[0021] Examples of organic fine particles include crosslinked acrylic particles, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polyethylene naphthalate, polystyrene, melamine resin, cyclic olefin copolymer, polyethylene sulfide, polyimide, polyethyl ether ketone, polyphenylene sulfide, cork, and wood flour. Crosslinked acrylic particles are particles of crosslinked acrylic resin. They may be homopolymers or copolymers of acrylic monomers, or copolymers of acrylic monomers and other monomers, and the method for producing the crosslinked acrylic particles is not particularly limited. Examples of such crosslinked acrylic particles include polymethyl acrylate, polyethyl acrylate, polymethacrylic acid, polymethyl methacrylate, and polyethyl methacrylate.

[0022] As the fine particles (C), one kind may be selected from the inorganic fine particles and organic fine particles and used alone, or two or more kinds may be selected and used in combination. When two or more kinds are used in combination, the inorganic fine particles and the organic fine particles may be mixed and used.

[0023] When the resin composition is used as a film, these fine particles (C) are incompatible with the ethylene-vinyl acetate copolymer (A) and the tackifier resin (B), and therefore, stress applied to the film can be absorbed by forming voids at the interfaces between the ethylene-vinyl acetate copolymer (A) and the tackifier resin (B) and the fine particles (C). That is, when the resin composition is used as a lid film for a plastic container, the stress generated when peeling the lid film from the container is absorbed by the formation of voids, requiring a stronger stress, and as a result, the adhesive strength can be improved.

[0024] The average primary particle diameter of the fine particles (C) is in the range of 0.001 to 1 μm, preferably in the range of 0.003 to 0.7 μm, and more preferably in the range of 0.005 to 0.5 μm. When the average primary particle diameter is 0.001 μm or more, aggregation of the fine particles is unlikely to occur and they are uniformly dispersed throughout the resin composition, which is preferable. When the average primary particle diameter is 1 μm or less, the transparency of the resin composition when made into a film is good, and further, the contact surface area between the ethylene-vinyl acetate copolymer (A) and the tackifier resin (B) and the fine particles (C) is sufficiently large, which is preferable because the adhesive strength to plastic containers is high.

[0025] In the present invention, the average primary particle diameter can be measured using a scanning electron microscope (FE-SEM), and if the resolution of the scanning electron microscope is low, it may be measured using another electron microscope such as a transmission electron microscope in combination. Specifically, if the particle shape is spherical, the diameter is considered to be the diameter, and if the particle shape is non-spherical, the average of the longest and shortest diameters is considered to be the diameter, and the average of the diameters of 20 particles randomly selected by observation using a scanning electron microscope or the like is taken to be the average primary particle diameter.

[0026] The blending ratios of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the fine particles (C) are as follows: Here, the total of (A), (B), and (C) is 100 parts by weight.

[0027] The blending ratio of the ethylene-vinyl acetate copolymer (A) is 50 to 94.5 parts by weight, preferably 52 to 90 parts by weight, and more preferably 60 to 87 parts by weight. When the blending ratio of (A) is 50 parts by weight or more, the resulting resin composition has excellent moldability, and when it is 94.5 parts by weight or less, the resulting resin composition has good adhesiveness.

[0028] The blending ratio of the tackifier resin (B) is 5 to 30 parts by weight, preferably 8 to 28 parts by weight, and more preferably 10 to 25 parts by weight. When the blending ratio of (B) is 5 parts by weight or more, the resulting resin composition has excellent adhesiveness, and when it is 30 parts by weight or less, blocking during molding processing is reduced.

[0029] The blending ratio of the fine particles (C) is 0.5 to 25 parts by weight, preferably 2 to 20 parts by weight, and more preferably 3 to 15 parts by weight. When the blending ratio of (C) is 0.5 part by weight or more, the resulting resin composition has excellent adhesiveness, and when it is 25 parts by weight or less, the resulting resin composition has excellent transparency and moldability.

[0030] The resin composition according to one embodiment of the present invention may further contain a compatibilizer (D). By including the compatibilizer (D), the fine particles (C) can be dispersed more uniformly in the resin composition, further improving the adhesive strength to various containers. Any compatibilizer (D) can be used as long as it exhibits such a compatibilizing effect. Examples of the compatibilizer (D) include oxidized polyolefins and acid group-modified polyolefins, which are obtained by partially oxidizing polyethylene, polypropylene, and copolymerized olefin resins thereof, and those obtained by reacting carboxylic acid groups such as maleic anhydride and itaconic anhydride.

[0031] Other examples of the compatibilizer (D) include thermoplastic block copolymers containing at least one of an olefin and a diolefin as a structural unit and a vinyl aromatic hydrocarbon as a structural unit. Such thermoplastic block copolymers are represented by the following formula: do.

[0032] (AB)n (AB)nA´ or (AB)mX (Here, A and A' each independently represent a vinyl aromatic hydrocarbon polymer block. B represents a polymer block of either an olefin or a diolefin. n represents an integer of 1 to 5, m represents an integer of 2 to 7, and X represents an m-valent polyfunctional compound.) The thermoplastic block copolymer is a polymer having at least one of a linear structure, a radial structure, and a branched structure, and having a block structure in which at least one end is a vinyl aromatic hydrocarbon polymer block. The thermoplastic block copolymer may be a hydrogenated product thereof.

[0033] Examples of the vinyl aromatic hydrocarbons used herein include styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene, vinylxylene, ethylvinylxylene, vinylnaphthalene, and mixtures thereof, etc. Among these, styrene is particularly preferred.

[0034] Examples of the olefins that can be used include α-olefins such as ethylene, propylene, and 1-butene, and examples of the diolefins that can be used include conjugated diolefins such as butadiene and isoprene.

[0035] As such a thermoplastic block copolymer, as long as olefin units predominate in block B, it is preferable to use a copolymer of either an olefin or a conjugated diolefin with a vinyl aromatic hydrocarbon, and it is more preferable to use a polymer block obtained by polymerizing a conjugated diolefin and hydrogenating it. Furthermore, in the present invention, a thermoplastic block copolymer of a vinyl aromatic hydrocarbon having vinyl aromatic hydrocarbon polymer blocks at both ends with an olefin or a diolefin is preferred, and in particular, a hydrogenated product of a polystyrene-polybutadiene-polystyrene block copolymer (styrene-ethylene / butylene-styrene triblock copolymer, hereinafter referred to as "hydrogenated SEBS") can be used particularly preferably from the viewpoint of improving thermal stability.

[0036] Although there are no particular limitations on such hydrogenated SEBS, the styrene content is preferably 1 to 50% by weight, more preferably 3 to 35%, and even more preferably 5 to 20% by weight, because the effect of the hydrogenated SEBS as a compatibilizer results in a resin composition with excellent adhesive strength. Furthermore, when a mixture of a hydrogenated styrene-butadiene diblock copolymer and a hydrogenated styrene-butadiene-styrene triblock copolymer is used as such hydrogenated SEBS, the mixing ratio is preferably 5 / 5 to 1 / 9.

[0037] As the compatibilizer (D), the above-mentioned compatibilizers may be used alone or in combination of two or more.

[0038] The blending ratio of the compatibilizer (D) is preferably 0.5 to 20 parts by weight, more preferably 0.8 to 18 parts by weight, and even more preferably 1 to 15 parts by weight, based on 100 parts by weight of the total of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the fine particles (C). When the blending ratio of (D) is 0.5 parts by weight or more, the resulting resin composition has excellent adhesive properties, and when it is 20 parts by weight or less, it is preferable because it has excellent cost performance and moldability.

[0039] The resin composition according to one embodiment of the present invention may further contain an ethylene-α-olefin copolymer (E). Any ethylene-α-olefin copolymer (E) can be used as long as it falls within the category generally referred to as an ethylene-α-olefin copolymer. The α-olefin is not particularly limited, but examples thereof include propene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and 1-dodecane, each having 3 to 12 carbon atoms. These ethylene-α-olefin copolymers (E) can be suitably produced by copolymerizing ethylene and an α-olefin using a Ziegler catalyst, a chromium catalyst, or a metallocene catalyst. Examples of polymerization methods include solution polymerization, high-pressure polymerization, and gas-phase polymerization.

[0040] Ethylene-α-olefin copolymer (E) has excellent peeling smoothness and sealing strength, and is used in applications with a density of 860 to 910 kg / m as measured in accordance with JIS K6922-1 (1998). 3 It is preferable that the range is:

[0041] The blending ratio of the ethylene-α-olefin copolymer (E) is preferably 5 to 100 parts by weight, more preferably 10 to 50 parts by weight, and even more preferably 15 to 40 parts by weight, based on 100 parts by weight of the total of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the fine particles (C).

[0042] The resin composition according to one embodiment of the present invention may further contain a low-density polyethylene (F).

[0043] The low-density polyethylene (F) is a low-density polyethylene obtained by polymerizing only ethylene using a known high-pressure polymerization method, and has a density range of 910 to 940 kg / m as measured according to JIS K6922-1. 3 The melting point of the low-density polyethylene (F) is preferably in the range of 98 to 120°C, more preferably in the range of 100 to 110°C.

[0044] The blending ratio of the low-density polyethylene (F) is preferably 5 to 100 parts by weight, more preferably 10 to 50 parts by weight, and even more preferably 15 to 40 parts by weight, relative to 100 parts by weight of the total of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the microparticles (C).

[0045] The low-density polyethylene (F) may be commercially available, for example, Petrothene (registered trademark) (manufactured by Tosoh Corporation), Novatec (registered trademark) LD (manufactured by Japan Polyethylene Corporation), and Sanwax (registered trademark) (manufactured by Sanyo Chemical Industries, Ltd.).

[0046] The resin composition of the present invention may be blended with other thermoplastic resins or rubbers, as well as light stabilizers, ultraviolet absorbers, nucleating agents, lubricants, antioxidants, antiblocking agents, flow improvers, mold release agents, flame retardants, colorants, inorganic neutralizing agents, hydrochloric acid absorbers, fillers, conductive agents, and the like, within the scope of not impairing the effects of the present invention.

[0047] There are no particular restrictions on the method for preparing the resin composition. For example, the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), the fine particles (C), and the materials to be added thereto are pre-blended simultaneously in a mixer such as a Henschel mixer or a tumbler, and then melt-kneaded in a single-screw or twin-screw extruder.

[0048] The sealant adhesive, which is one embodiment of the present invention, will be described in detail below.

[0049] The resin composition can be used as an adhesive. In particular, the resin composition can be suitably used as a sealant adhesive for plastic containers whose main components are resins such as polyethylene terephthalate, polystyrene, polypropylene, etc., and various other resins, particularly as a lid sealant adhesive. Here, "sealant" means that it is used for sealing a container. By using the lid sealant adhesive, the lid and the container can be sealed.

[0050] Specific examples of materials for the plastic container include polyolefin resins, acrylic acid resins, polyamide resins, polyester resins, polycarbonate resins, polystyrene resins, styrene-acrylonitrile copolymers, and polyvinyl chloride resins.

[0051] Examples of polyolefin resins include low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, and polypropylene.

[0052] Examples of the acrylic acid resin include polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polyoctyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, and polyoctyl methacrylate.

[0053] Examples of polyamide resins include nylon 6, nylon 6,6, nylon 11, and nylon 12.

[0054] Examples of polyester resins include polyethylene terephthalate (amorphous polyethylene terephthalate, crystalline polyethylene terephthalate), polybutylene terephthalate, polylactic acid (including poly-L-lactic acid, poly-D-lactic acid, copolymers of L-lactic acid and D-lactic acid, and stereocomplexes of poly-L-lactic acid and poly-D-lactic acid), polybutylene succinate, poly(butylene succinate / adipate), polyethylene succinate, poly(butylene succinate / terephthalate), poly(butylene adipate / terephthalate), poly(hydroxybutyrate / hydroxyhexanoate), polyglycolic acid, poly 3-hydroxybutyrate, and polycaprolactone.

[0055] When the resin composition is used as an adhesive for adhering a plastic container containing these materials, the main component of the plastic container may be a single component or a composition of multiple resins. The container may also be a multi-layered laminate of multiple materials.

[0056] The resin composition can be suitably used for containers made of polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, or polylactic acid.

[0057] The lid material according to one embodiment of the present invention will be described in detail below.

[0058] When the resin composition is used as an adhesive, it is preferably used as an adhesive layer containing the resin composition (hereinafter referred to as a "sealant adhesive layer").Furthermore, it can be suitably used as a lid material having a configuration including at least two layers, a supporting substrate layer and a sealant adhesive layer, with the sealant adhesive layer being the outermost layer.

[0059] The support substrate constituting the support substrate layer is not particularly limited as long as it is self-supporting, and examples thereof include olefin resins such as polyethylene, polypropylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, and saponified ethylene-vinyl acetate copolymer, polyethylene terephthalate, polybutylene terephthalate, polylactic acid (including poly-L-lactic acid, poly-D-lactic acid, copolymers of L-lactic acid and D-lactic acid, and stereocomplexes of poly-L-lactic acid and poly-D-lactic acid), polybutylene succinate, poly(butylene succinate / adipate), polyethylene succinate, poly(butylene Examples of the support substrate layer include plastic films made of thermoplastic resins such as polyester resins (e.g., poly(3-hydroxybutyrate / hydroxyhexanoate), polyglycolic acid, poly(3-hydroxybutyrate), and polycaprolactone), polyamide resins (e.g., nylon 6, nylon 6,6, nylon 11, and nylon 12), paper (e.g., Japanese paper and composite paper), metal foil made of aluminum or other metals, vapor-deposited films in which aluminum or silica is vapor-deposited on the surface of polyester resin films, and films made of these alone or laminates. The thickness of the support substrate layer can be selected depending on the application as long as it does not impair mechanical strength, workability, etc., but is generally about 5 to 100 μm, and preferably 10 to 50 μm.

[0060] When used as a lid material, the thickness of the sealant adhesive layer can be selected depending on the application as long as the adhesiveness, workability, etc. are not impaired, but is generally about 5 to 50 μm, preferably 10 μm to 40 μm, and more preferably 15 to 30 μm.

[0061] The lid material may also include an intermediate layer between the support substrate layer and the sealant adhesive layer to enhance adhesion between the two layers. This intermediate layer may be composed of components such as thermoplastic resins, such as polyolefins, and thermoplastic elastomers, and these components may be used alone or in combination. Examples of polyolefins include polyethylene and ethylene copolymers (e.g., ethylene-α-olefin copolymers, propylene-ethylene copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, and ethylene-methyl acrylate copolymers), as well as modified products thereof. The intermediate layer may also contain various additives, such as antioxidants, lubricants, antistatic agents, conductive agents, antiblocking agents, and tackifiers, as long as they do not impair the effects of the present invention.

[0062] The thickness of the intermediate layer can be selected depending on the application as long as workability is not impaired, but is generally about 5 to 30 μm.

[0063] An anchor coat layer of polyurethane or the like can be provided between the supporting substrate layer and the sealant adhesive layer, or between the supporting substrate layer and the intermediate layer, in order to improve adhesion between the two layers.

[0064] A lid material having a sealant adhesive layer as the outermost layer is suitable as a lid material for various types of plastic containers, and combines high adhesive strength with transparency.

[0065] The method for producing the lid material is not particularly limited, but examples thereof include a method of laminating the sealant adhesive and the supporting substrate layer, and a method of co-extruding the sealant adhesive and the supporting substrate layer.

[0066] Examples of lamination methods include: (1) an extrusion lamination method in which an anchor coating agent is applied to a supporting substrate layer and an adhesive layer is melt-extruded; (2) an extrusion lamination method in which an anchor coating agent is applied to a supporting substrate layer and an intermediate layer is melt-extruded, and then a sealant adhesive layer is melt-extruded thereon; (3) an extrusion lamination method in which an intermediate layer having excellent adhesion to the supporting substrate, such as an ethylene-methacrylic acid copolymer or an ethylene-methyl methacrylate copolymer, is melt-extruded onto the supporting substrate layer and then a sealant adhesive layer is melt-extruded thereon; (4) a co-extrusion lamination method in which an anchor coating agent is applied to a supporting substrate layer and then the intermediate layer and adhesive layer are melt-extruded simultaneously; and (5) (6) dry lamination, in which a film containing at least one layer of sealant adhesive is formed in advance by inflation or cast molding and then bonded to a support substrate layer coated with an anchor coating agent; and (7) sandwich extrusion lamination, in which an intermediate layer is melt-extruded between a support substrate layer coated with an anchor coating agent and a film containing at least one layer of sealant adhesive using extrusion lamination. Meanwhile, examples of methods for co-extruding a sealant adhesive and a support substrate layer include the co-extrusion inflation method and the co-extrusion T-die method. [Example]

[0067] The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples.

[0068] The adhesive strength, sealing strength and internal haze of the lid materials obtained in the examples were measured by the methods described below.

[0069] (Measurement of adhesive strength) The adhesive surface of the lid material was overlapped with a 0.35 mm thick A-PET sheet (manufactured by Toyobo Co., Ltd.) and pressure-heat bonded using a heat seal tester (Tester Sangyo Co., Ltd., Model TP-701) at 160°C, 0.2 MPa, and 1 second. After cooling at room temperature, the adhesive strength was measured at a peel angle of 180° and a peel speed of 300 mm / min. The adhesive strength was also measured using a similar method on a 0.35 mm thick silicone-coated A-PET sheet (manufactured by Mineron Kasei Co., Ltd.) whose surface was silicone-coated. The adhesive strength should preferably be 10 N / 15 mm or greater to prevent leakage of contents during transportation and storage.

[0070] (Sealing strength measurement) The adhesive surface of the lid material was placed over an A-PET cup (manufactured by Rispack, 101 mm diameter, 210 ml capacity) and pressure-heated and bonded using a cup sealing machine (manufactured by Sunny Cup, model UF-500) at 160°C, 0.2 MPa, and 1 second. After cooling, the burst strength was measured using a seal tester (manufactured by Sun Scientific, model FKT-100J) with an air injection rate of 0.8 L / min. The strength measured here was taken as the sealing strength. The sealing strength is preferably 10 kPa or more to prevent leakage of the contents during transportation and storage.

[0071] (Internal Haze Measurement) The internal haze was measured by wetting the measurement points on the front and back surfaces of the lid material with liquid paraffin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and sandwiching the material between two glass slides. The measurement was carried out in accordance with JIS K7136 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., Model NDH7000). The internal haze is preferably 20% or less, and more preferably 15% or less, since packaging materials using the resulting lid material will have excellent visibility of the contents.

[0072] Example 1 75 parts by weight of resin (A1) (manufactured by Tosoh Corporation, trade name Ultrathene (registered trademark) 537) having a vinyl acetate content of 5.5% by weight and a melt mass-flow rate of 8.5 g / 10 min as the ethylene-vinyl acetate copolymer (A), 15 parts by weight of fully hydrogenated petroleum resin (B1) (manufactured by Arakawa Chemical Industries, Ltd., trade name Alcon (registered trademark) P125; softening temperature 125°C) as the tackifier resin (B), and 10 parts by weight of calcium carbonate (C1) (manufactured by Shiraishi Kogyo Co., Ltd., trade name Viscoexcel 30) having an average primary particle diameter of 0.03 μm as the fine particles (C) were pre-blended in a tumbler mixer, and then melt-kneaded at 160°C using a twin-screw extruder to obtain pellets of a resin composition.

[0073] Thereafter, a biaxially oriented polyester film (thickness 12 μm) serving as a support substrate layer was extrusion-laminated with a low-density polyethylene intermediate layer (thickness 25 μm, manufactured by Tosoh Corporation under the trade name Petrothene® 203). The resin composition pellets were extrusion-laminated onto the low-density polyethylene surface of the resulting two-layer film using an extrusion laminator (manufactured by Sumitomo Heavy Industries Modern Co., Ltd., screw diameter 40 mm) at a processing temperature of 240°C to obtain a lid material with a resin composition layer thickness of 20 μm. The evaluation results of the obtained resin composition and the lid material are shown in Table 1.

[0074] Example 2 A resin composition and a lid material were obtained in the same manner as in Example 1, except that the ethylene-vinyl acetate copolymer (A1) was changed to 82 parts by weight, the tackifier resin (B1) to 15 parts by weight, and the fine particles (C1) to 3 parts by weight in Example 1. The evaluation results of the obtained resin composition and the lid material are shown in Table 1.

[0075] Example 3 A resin composition and a lid material were obtained in the same manner as in Example 1, except that 5 parts by weight of a thermoplastic block copolymer (D1) (Kraton (registered trademark) G1726VS) of vinyl aromatic hydrocarbon and diolefin, in which the mixing ratio of hydrogenated styrene-butadiene diblock copolymer and hydrogenated styrene-butadiene-styrene triblock copolymer was 7 / 3 and the styrene content was 30% by weight, was further blended into the resin composition consisting of the ethylene-vinyl acetate copolymer (A1), tackifier resin (B1), and fine particles (C1) of Example 1. The evaluation results of the obtained resin composition and the lid material are shown in Table 1.

[0076] Example 4 A resin composition and a lid material were obtained in the same manner as in Example 3, except that 10 parts by weight of calcium carbonate (C2) (manufactured by Shiraishi Kogyo Co., Ltd., trade name CALSHITEC (registered trademark) Vigot 15) having an average primary particle diameter of 0.15 μm was blended in place of the fine particles (C1). The evaluation results of the obtained resin composition and lid material are shown in Table 1.

[0077] Example 5 The resin composition of Example 3, which is composed of the ethylene-vinyl acetate copolymer (A1), the tackifier resin (B1), the fine particles (C1), and the compatibilizer (D1), was further treated with an ethylene-α-olefin copolymer (E) having a density of 860 kg / m 3 A resin composition and a lid material were obtained in the same manner as in Example 3, except that 20 parts by weight of an ethylene-α-olefin copolymer (E1) (manufactured by Mitsui Chemicals, Inc., trade name: Tafmer (registered trademark) P-0375) was added. The evaluation results of the obtained resin composition and lid material are shown in Table 1.

[0078] Example 6 The resin composition of Example 4, which is composed of the ethylene-vinyl acetate copolymer (A1), the tackifier resin (B1), the fine particles (C1), and the compatibilizer (D1), was further treated with a low-density polyethylene (F) having a density of 919 kg / m 3A resin composition and a lid material were obtained in the same manner as in Example 3, except that 20 parts by weight of low-density polyethylene (F1) (manufactured by Tosoh Corporation, trade name Petrothene (registered trademark) 203) having a melt mass-flow rate of 8.0 g / 10 min and a melting point of 105°C was blended. The evaluation results of the obtained resin composition and lid material are shown in Table 1.

[0079] Example 7 A resin composition and a lid material were obtained in the same manner as in Example 3, except that 5 parts by weight of a thermoplastic block copolymer (D2) (Kraton (registered trademark) G1657VS) of a vinyl aromatic hydrocarbon and a diolefin, having a styrene content of 13% by weight and a mixing ratio of hydrogenated styrene-butadiene-diblock copolymer to hydrogenated styrene-butadiene-styrene-triblock copolymer of 3 / 7, was blended in place of the compatibilizer (D1).

[0080] Comparative Example 1 A resin composition and a lid material were obtained in the same manner as in Example 1, except that the amount of ethylene-vinyl acetate copolymer (A1) was changed to 85 parts by weight and the amount of tackifier resin (B1) was changed to 15 parts by weight.

[0081] The evaluation results of the obtained resin composition and lid material are shown in Table 1. The obtained lid material was poor in adhesive strength and sealing strength.

[0082] Comparative Example 2 A resin composition and a lid material were obtained in the same manner as in Example 3, except that the ethylene-vinyl acetate copolymer (A1) was changed to 55 parts by weight, the tackifier resin (B-1) to 15 parts by weight, the microparticles (C1) to 30 parts by weight, and the compatibilizer (D1) to 5 parts by weight.

[0083] The evaluation results of the obtained resin composition and lid material are shown in Table 1. The obtained lid material was poor in transparency.

[0084] Comparative Example 3 A resin composition and a lid material were obtained in the same manner as in Example 1, except that 10 parts by weight of calcium carbonate (C3) (manufactured by Shiraishi Kogyo Co., Ltd., trade name Whiten (registered trademark) P30) having an average primary particle diameter of 4 μm was blended in place of the fine particles (C1). The evaluation results of the obtained resin composition and lid material are shown in Table 1. The obtained lid material was poor in adhesive strength, sealing strength, and transparency.

[0085] [Table 1]

Claims

1. A resin composition comprising 50 to 94.5 parts by weight of an ethylene-vinyl acetate copolymer (A), 5 to 30 parts by weight of a tackifier resin (B), and 0.5 to 25 parts by weight of fine particles (C) having an average primary particle size in the range of 0.001 to 1 μm (wherein the total of (A), (B), and (C) is 100 parts by weight).

2. The resin composition according to claim 1, further comprising 0.5 to 20 parts by weight of a compatibilizer (D) relative to 100 parts by weight of the resin composition.

3. 3. The resin composition according to claim 2, wherein the compatibilizer (D) is a hydrogenated polystyrene-polybutadiene-polystyrene block copolymer and has a styrene content of 5 to 20% by weight.

4. Further, the density measured by JIS K6922-1 is 860 to 910 kg / m for 100 parts by weight of the resin composition. ３ 2. The resin composition according to claim 1, comprising 5 to 100 parts by weight of an ethylene / α-olefin copolymer (E) in the range of:

5. Further, a density measured according to JIS K6922-1 of 910 to 940 kg / m for 100 parts by weight of the resin composition ３ and 5 to 100 parts by weight of a low-density polyethylene (F) having a melting point in the range of 98 to 120°C as measured according to JIS K6924-2.

6. 2. The resin composition according to claim 1, wherein the tackifier resin (B) is at least one selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymer petroleum resins.

7. The resin composition according to claim 1, wherein the fine particles (C) are calcium carbonate.

8. A sealant adhesive comprising the resin composition according to any one of claims 1 to 7.

9. 9. The sealant adhesive according to claim 8, which is for a container made of at least one resin selected from the group consisting of polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, and polylactic acid.

10. A lid material comprising at least two layers: a layer containing the resin composition according to any one of claims 1 to 7, and a supporting substrate layer.

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